Euan’s mum Ann, 44, who works with the homeless and the disadvantaged, said: “We brought Euan and his sister Mhairi up to understand right and wrong.

“We taught them both that, if you always do your best, things will work out the way they should.

“Can you imagine how hard it’s been for us to try to explain to Mhairi that her brother’s life was worth so little in the eyes of the court? We will never give up fighting for our son. We simply cannot let this go.”

The Craigs are meeting Labour MSP Lewis Macdonald next week to raise their concerns.

He said: “We see victims and their families going through the trauma of hearing defence lawyers painting the defendant in the best light and often victims in the worst light.

“There is no one speaking up for victims in court. The prosecution do not see it as their role.” Ann said: “The defence said Euan died because of what may have passed off as just a school fight. There was no fight.